Tuesday, June 6, 2017

A gorgeous, fully mature Leuctrid (Needlefly, Rolled-winged stonefly)

I think this is the first time that I found a Leuctrid that was fully mature -- wing-pads are totally black.  Gorgeous colors.

Before this, the closest I got was one with "tan" wing-pads -- the stage before they turn black.  (photo from 5/30/12)

At 5.5 mm, it's a very small stonefly.  They're numerous in the small mountain streams in Sugar Hollow, and it seems that we see them all season long.  But we've clearly moved into the time of year when some of them -- there may be a different species that we see throughout the summer -- mature and hatch.  Tolerance value of 1.5.  It's one that we have to leave at the level of genus -- Leuctra.  Beaty notes that there are at least 10 species of Leuctra in North Carolina, many of which remain undescribed.  ("The Plecoptera of North Carolina," p. 11)


But that Leuctrid is only one of the insects I ran into this morning that was mature and ready to hatch.  Another -- this prong-gilled mayfly, Paraleptophlebia.

And I found a second prong-gilled mayfly that was clearly some other species.  This one.

The differences between these two nymphs is rather pronounced.  They differ in color, length, abdominal shape, and overall pattern.  Compare.

The burnt orange nymph -- the one with the black wing-pads -- measured 4 mm; the dull brown nymph was 5.  I think you can also tell from this photo that the head patterns are very different.

Species ID?  I haven't tried it, but I might give it a go.  According to Beaty, "With species descriptions from Randolph and McCafferty (1996), the Unzicker and Carlson (1982) key can be used to separate out nine potential NC species." ("The Ephemeroptera of North Carolina," p. 79)  Sounds like a project for a rainy day.

Until then, I've noted before that were we to use the photos provided in DiscoverLife (http://www.discoverlife.org/mp/20q?search=Paraleptophlebia), we might conclude that the burnt-orange nymph

was P. mollis, while the dull brown nymph

was P. guttata.  Still, we can't go by pigmentation alone.  Time to get to work with that key.

One more nymph with darkening wing-pads, though not yet completely mature.

I thought this might be an early Epeorus vitreus nymph, but it turned out to be a late-blooming Epeorus pleuralis.

Oh.  My good friend who lives in Sugar Hollow has recently sent me some photos of a stonefly adult that she thought might be a Leuctrid.

Sure looks that way to me.  Much prettier as nymphs -- yes?!

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